Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/20—Output circuits, e.g. for controlling currents in command coils
  • F02D41/2096—Output circuits, e.g. for controlling currents in command coils for controlling piezoelectric injectors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/20—Output circuits, e.g. for controlling currents in command coils
  • F02D2041/202—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit
  • F02D2041/2051—Output circuits, e.g. for controlling currents in command coils characterised by the control of the circuit using voltage control

Definitions

• the invention relates to a method for operating an injection valve, in particular a fuel injection valve of an internal combustion engine of a motor vehicle, wherein the injection valve has a piezoelectric actuator for driving a with the actuator, preferably hydraulically coupled valve needle.
• Injectors and methods of this type are known and usually include presetting an actuator voltage to which the piezoelectric actuator is to be loaded or reloaded to move the valve needle of the injector to a desired position or to put the injector in a desired operating condition , Due to aging effects in particular of the piezoelectric actuator itself and the mechanical and hydraulic components contained in the injection valve, however, changes in the corresponding electrical or mechanical parameters of the injection valve result, so that, for example, the precise metering of an amount of fuel to be injected using the known methods in the long term not possible is.
• an actuator stroke caused by the piezoelectric actuator is approximately proportional to a corresponding voltage swing of the actuator voltage, regardless of aging effects of the piezoelectric actuator or, for example, a temperature-related change in the electrical capacitance of the piezoelectric actuator.
• the actuator of a further embodiment of the According to the method according to the invention can be reloaded in a predefinable recharging with a dependent of the voltage swing Umladestrom. This ensures that the same predefinable recharging time is required for each transshipment, while the Umladestrom required for reloading the actuator can be selected accordingly.
• a multiplicity of possible movement profiles of the valve needle during the transfer from a first operating state to a second operating state can be advantageously set.
• characteristic working or lifting positions of the valve needle can be regulated or even equalized among several injection valves.
• Length which is less than the first length, shortened to transfer the injector from its closed state to its open state.
• a reaction to the actuator exerts which increases the actuator voltage by a feedback voltage
• the voltage swing is selected such that a desired feedback voltage results.
• the reaction of the valve needle to the actuator is caused by the fact that the valve needle, after one end of the energization of the actuator, initially moves further toward the actuator and exerts a corresponding force on the actuator, which is essentially at rest after the energization end, which is the piezoelectric actuator Effect corresponding to the feedback voltage leads.
• the specification according to the invention of the voltage lift used to open the injection valve allows a conclusion on the actuator stroke corresponding to the voltage swing and thus also on the path traveled by the valve needle during the opening process of the actuator Injector or while energizing the actuator.
• the valve needle With a relatively large voltage swing used for discharging the actuator or for opening the injection valve, the valve needle has already covered a corresponding, relatively large path away from its valve seat on its Nadelhubanschlag during actuation of the actuator, so that they subsequently only a relatively small way must travel back to their Nadelhubanschlag and this causes a correspondingly relatively low feedback voltage.
• the valve needle With a comparatively small selected voltage stroke for the opening process of the injection valve, the valve needle accordingly has a longer path up to its needle stroke stop after the end of the energization, so that a comparatively large reaction voltage also occurs. Due to the corresponding choice of the voltage stroke according to the invention, it is therefore advantageously possible to determine the remaining after the Bestromungsende path of the valve needle to her Nadelhubanschlag and thus the timing of impact of the valve needle on the Nadelhubanschlag, which, for example, over several operating cycles of the injector away or. even over the entire operating time a precise injection of fuel is feasible.
• the inventive method can also be advantageously used to equalize the time of reaching the respective Nadelhubanzzis by the valve needles of a plurality of injectors to adjust their injection behavior or the injected through them fluid quantities to each other.
• the voltage swing is selected such that the valve needle reaches the valve seat and / or a needle lift stop when the energization of the actuator is terminated.
• the voltage swing for driving the actuator is selected so that an amount of the first time derivative of the actuator voltage is minimal between one end of the current supply of the actuator and a first change of sign of the first time derivative of the actuator voltage since the end of the energization of the actuator, the above described configuration in which the achievement of a valve seat or the Nadelhubanschlags takes place simultaneously with the end of the energization of the actuator, particularly precisely realized.
• a recharging time which is required for the transfer of the injection valve from its open state to its closed state, regulated, whereby a precise maintenance of the recharging time ensured even with changing properties of the injection valve and the piezoelectric actuator is.
• the recharging time of a further variant of the invention can be selected as a function of a desired closing time, within which the valve needle moves from an initial position to its valve seat.
• the regulation of the voltage stroke according to the invention is preferably carried out for each operating cycle of the injection valve, so that a particularly high accuracy in the control is achieved. Also, the above-mentioned recharging time can be controlled according to the invention advantageously for each operating cycle of the injector.
• the regulation of the feedback voltage and / or the regulation of the first time derivative of the actuator voltage between an end of the energization of the actuator and a first change of sign of the first time derivative of the actuator voltage since the end of the energization of the actuator and / or the control of the closing time is advantageously carried out in every n-th operating cycle of the injection valve, where n> 1, so that corresponding steps of the respective control method need not be performed in each operating cycle of the injector, which in particular resources of the control method exporting processing unit are spared, for example, in a the Injector controlling control unit is integrated.
• the computer program may be stored, for example, on an electronic storage medium, wherein the storage medium in turn may be contained for example in the control unit.
• Figure 1 is a schematic sectional view of an embodiment of a
• FIG. 2 a schematically shows a time profile of an actuator voltage of a piezoelectric actuator of the fuel injection valve from FIG. 1,
• 3a shows a detailed representation of the time course of the first temporal
• 3b shows a detailed representation of the time profile of the second time derivative of the actuator voltage of the piezoelectric actuator
• FIG. 4a schematically shows a functional diagram of a controller structure for
• FIG. 4b schematically shows a functional diagram of a controller structure for implementing a further embodiment of the method according to the invention
• Figures 5a to 5c each further examples of a time course of
• FIG. 6 schematically shows a functional diagram of a further controller structure of a third embodiment of the method according to the invention.
• FIG. 1 shows an injection valve, designed as a fuel injection valve 10, of an internal combustion engine of a motor vehicle, which is provided with a piezoelectric actuator 12.
• the piezoelectric actuator 12 is driven by a control device 20 as indicated in FIG. 1 by the arrow. Furthermore, the
• Fuel injection valve 10 a valve needle 13 which can sit on a valve seat 14 a in the interior of the housing of the fuel injection valve 10.
• a fully opened state of the fuel injection valve 10 is characterized in that the valve needle 13 is arranged on a needle stroke stop arranged in the region 14b and not shown, which prevents further movement of the valve needle 13 away from its valve seat 14a, ie towards the actuator 12 , If the valve needle 13 is seated on the valve seat 14a, the fuel injection valve 10 is closed. That is, the entire, in the figure of Figure 1 vertically extending, stroke, the valve needle 13 can cover is limited on the one hand by the valve seat 14a (closed position) and on the other hand by the Nadelhubanschlag in the area 14b (open position).
• the transition from the closed to the open state is effected by means of the piezoelectric actuator 12.
• a voltage referred to below as the actuator voltage U is applied to the actuator 12, which causes a change in length of a arranged in the actuator 12 piezo stack, which in turn is used to open or close the fuel injection valve 10.
• the fuel injection valve 10 further includes a hydraulic coupler 15.
• the hydraulic coupler 15 is disposed within the fuel injection valve 10 and has a coupler housing 16 in which two pistons 17, 18 are guided.
• the piston 17 is connected to the actuator 12 and the piston 18 is connected to the valve needle 13.
• a volume 19 is included, which accomplishes the transmission of the force exerted by the actuator 12 on the valve needle 13.
• the coupler 15 is surrounded by pressurized fuel 11.
• the volume 19 is also filled with fuel. Via the guide gaps between the two pistons 17, 18 and the coupler housing 16, the volume 19 can be adapted over a longer period of time to the respectively existing length of the actuator 12. For short-term changes in the length of the actuator 12, however, the volume 19 remains virtually unchanged and the change in the length of the actuator 12 is transmitted to the valve needle 13.
• Figure 2a schematically shows the time course of the actuator voltage U for driving the piezoelectric actuator 12 of the injection valve 10 of Figure 1 again. As can be seen from FIG.
• the actuator voltage U is lowered starting from the time e in the context of the method according to the invention starting from an output voltage U 0 by a voltage swing symbolized by the double arrow .DELTA.U to a corresponding target voltage U.sub.i, which can also be seen from FIG Time ti to the piezoelectric actuator 12 ( Figure 1) is applied.
• energization of the actuator 12 which is not apparent from FIG. 2a, ie an application of the actuator 12 with a discharge current corresponding to the voltage swing .DELTA.U, is also set.
• the valve needle 13 continues to move toward its needle stroke stop 14b located in the region of the coupler housing 16 and in this case exerts a corresponding force on the piezoelectric actuator 12.
• This force is metrologically detected by the hereinafter also referred to as feedback voltage voltage .DELTA.U R , which is superimposed on the actual actuator voltage U of the actuator 12 and this changed.
• the valve needle 13 has reached its Nadelhubanschlag 14b and thus assumed its rest position corresponding to a fully open state of the injection valve 10. Accordingly, the valve needle 13 now exerts no further pressure on the actuator 12, and it turns from the time X 2 which is also referred to as a plateau voltage substantially time constant voltage U p .
• the piezoelectric actuator 12 is driven again, in particular charged by a corresponding charging current, so that up to the time t 5, the actuator voltage U increases again to the value of the output voltage U 0 .
• the actuator 12 undergoes the length change already described above, which moves the valve needle 13 from its rest position on the Nadelhubanschlag 14b again to its valve seat 14a, whereby the closed position of the injector 10 and its closed operating state is characterized.
• FIG. 2 b additionally shows a time-related characteristic of the actuator voltage U of the actuator 12 that is measured, comparable to the schematic illustration from FIG.
• the reloading of the actuator 12 according to the invention by triggering with a predefinable voltage swing .DELTA.U (FIG. 2a) or a corresponding charge-reversal current I enables a particularly precise control of the valve needle 13 and thus, for example, a particularly precise metering of fuel through the injection valve 10.
• a corresponding controller structure is shown schematically in FIG. 4a.
• the first part of the Rl illustrated in Figure 4a controller receives as a desired size to be adjusted voltage swing .DELTA.U S0 n, in an unspecified subtractor together with the actually occurring voltage swing .DELTA.U
• This control difference is fed to a function block 30, which may for example be formed as a characteristic or characteristic map and transforms the control difference into a discharge current I E , with which the piezoelectric actuator 12 is to be controlled in a subsequent control cycle to the control difference ⁇ U S oi ⁇ - .DELTA.U
• the discharge current I E is supplied to a function block representing the injection valve 10, and the quantities of actuator voltage U and actuator current I resulting from the triggering with the discharge current I E , which are detected, for example, by the control unit 20 (FIG. 1), are also preferably one in the control unit 20 realized evaluation unit 25 supplied.
• the evaluation unit 25 determines, on the one hand, the actual voltage deviation ⁇ U
• a comparable voltage swing .DELTA.U can also be used, for example, to charge the actuator 12, in particular in order to shift the injection valve 10 from an open state to a closed state.
• the controller Rl described above can be used.
• the regulation according to the invention of the voltage swing .DELTA.U always ensures that a desired actuator stroke h is established, independently of aging effects of the piezoelectric actuator 12 and / or of the further components of the injection valve 10.
• the inventive specification of the voltage .DELTA.U is - in addition to the defined transhipment of the actuator 12 - advantageously determines which way the valve needle 13, starting from its closed position on the valve seat 14a during the intended for discharging Bestromungszeit travels to ti ( Figure 2a).
• this also fixes the remaining travel of the valve needle 13 as far as its needle stroke stop 14b, which it covers in time ti to t 2 .
• a regulation of the opening time t 2 -towird by the inventive, also shown in Figure 4a additional control circuit R2 allows.
• a target value ⁇ U RSO ⁇ is set, which determines the desired feedback voltage ⁇ U R and accordingly also influences the time difference t 2 -ti and thus also t 2 itself.
• a corresponding control difference .DELTA.U Rs0 ⁇ is again - .DELTA.U RLST formed for the feedback voltage which is fed to a function block 31, and thereby transformed into a corresponding desired value for the invention to be adjusted voltage swing .DELTA.U ,
• FIG. 3 a shows a time profile of the actuator voltage U for the actuator 12 in the time range between approximately t 1 and t 2 in FIG. 2 a .
• the time designated in FIG. 3a by the reference symbol t B ⁇ indicates the end of a current supply to the actuator 12 and thus corresponds to the time indicated in FIG. 2 a by the reference symbol ti.
• the Bestromungsende t BE sign change of the first time derivative U of the actuator voltage U is evaluated and as a feature for achieving the
• a recharging time which is required for the transfer of the injection valve 10 from its open state into its closed state, is regulated.
• the reloading time in question can be seen from Figure 2a as a time difference between the times t 3 and t 5 .
• the inventive regulation of the recharging time allows a particularly precise closing of the injection valve 10 and can be advantageously implemented by the regulator structure shown in FIG. 4b.
• the recharging time to be set, within which the injection valve 10 is to be transferred from its open state (time I 3 ) to its fully closed state (time t 5 ), is symbolized in FIG. 2a by the double arrow At 35S0H .
• a corresponding desired value At 35S0N for this recharging time is supplied to the regulator R3 shown in FIG. 4b and, together with a corresponding actual quantity At 35ISt determined by the evaluation unit 25, is processed in a manner known per se to a corresponding control difference which is fed to a downstream functional block 32.
• the function block 32 transforms the control difference into a charging current I L , with which the actuator 12 is to be charged during the recharging time t 5 - 1 3 in order to maintain the desired recharging time At 35S0N .
• the actuator 12 At the end t 5 (FIG. 2 a ) of the recharging time, the actuator 12 is charged again to its output voltage U 0 and ready for a renewed operating cycle, ie for a subsequent discharge.
• valve needle 13 during the recharging time t 5 - achieved h designated time - 1 3 but at an earlier point in time T I its valve seat 14a ( Figure 1), that is, the completely closed operating state of the injection valve 10 is already after a below T I as a closing time ,
• the valve needle 13 likewise exerts an already above in connection with the opening operation or reaching the stroke stop 14b described feedback effect on the actuator 12, which is detected as a change of the first time derivative U, ie as a kink, the actuator voltage U.
• a precise control of the actual closing time t ⁇ - h according to the invention is achieved in that a value corresponding to the desired closing time At 3450I i for the recharge time At 35S0H is specified. This is done by the regulator R4, likewise shown in FIG. 4b, whose corresponding control difference At 3450H ⁇ At 34ISt is transformed in a function block 33 into the corresponding setpoint At 3550H for the reloading time.
• the regulator R 3 may also be active during each operating cycle of the injection valve 10, ie, during each charging process of the actuator 12, while the regulator R 4 may be active only in every n-th charging process of the actuator 12 is. This is particularly advantageous because the detection according to the invention of the time I 4 , to which the valve needle 13 meets its valve seat 14 a based on an evaluation of the second time derivative U of the actuator voltage U of the actuator 12 and accordingly requires a greater amount of computation than the processing of Sizes U, I used in controller R3.
• R3 evaluation unit 25 As far as the time derivatives of the actuator voltage U are determined by the indicated within the controller Rl, R3 evaluation unit 25, such a determination takes place according to only every n operating cycles, although the calculation of further, required for the operation of the controller Rl, R3 sizes as described preferably takes place in each operating cycle.
• FIG. 3b shows a detailed view of the time profile of the second time derivative U of the actuator voltage U of the actuator 12.
• the evaluation unit 25 of the controller structure shown in FIG. 4b accordingly evaluates the second time derivative Ü, determines the closing time tsc hh eß (FIG. 3b) and, as shown in FIG. 4b, forms the quantity ⁇ t3 4 , st .
• the evaluation of the actual closing time t SChh eß according to Figure 3b may alternatively be carried out by an analysis of the first time derivative of the actuator voltage U or equivalent, known in the art, measures.
• FIGS. 5a and 5b illustrate further time courses of the actuator voltage U, as they can occur during the operation of the injection valve 10.
• a particularly advantageous variant of the operating method according to the invention provides that the voltage swing .DELTA.U is selected so that the first time derivative U of the actuator voltage U or the amount thereof is minimal between an end t B ⁇ ( FIG. 3 a) of the energization of the actuator 12 and a first sign change t V zw (FIG. 3 a) of the first time derivative U of the actuator voltage U since the end t B ⁇ of the energization of the actuator 12.
• the method according to the invention analyzes the first time derivative U of the actuator voltage U of the actuator 12 and minimizes these in the time range t V between t BE in question . to which the valve needle 13 strikes the valve seat 14a and the Nadelhubanschlag 14b.
• the first time derivative of the actuator voltage U is determined, cf. the size U ⁇ st the regulator R5, R6 of FIG 6.
• the value zero is used as reference value U soll determined, and a corresponding error signal is supplied to the function block 26 of the controller R6.
• the function block 26 forms an average over the control difference of the last, for example, three previous operating cycles of the injection valve 10. This mean value is transformed by the downstream function block 35 into a desired value for a voltage deviation ⁇ U S0 n to be set according to the invention
• Minimization of the first time derivative U of the actuator voltage U causes the end of a respective transfer operation.
• Valve needle 13 the respective, their stroke limiting element 14a, 14b contacted.
• a mean value formation of the relevant control difference can also be provided in the controllers R2 (FIG. 4a), R4 (FIG. 4b) in order to increase the stability of the respective controller.
• the downstream controllers R1, R3 are preferably designed to operate faster than the higher-level controller R2, R4. This may be as already described above e.g. be achieved by an appropriate design of the cycle time for the higher-level controller R2, R4, which are preferably activated only every n-th operating cycle. In the sense of a particularly fast control by the downstream controllers Rl, R3, in this case also no averaging of the respective control difference is preferably provided.
• the regulators R 1,..., R 4 can have any suitable characteristic for the above operating purposes, in particular a P (proportional) behavior and / or an I (integral) behavior being considered.
• the inventive method allows by controlling the voltage .DELTA.U advantageously advantageous, for example, a precise constant holding the voltage .DELTA.U, so that the effects of temperature-induced changes in the properties of the actuator 12, resulting for example during operation, reduced to a fuel quantity actually injected or completely compensated , That is, by the inventive control of the voltage .DELTA.U to a predetermined, preferably constant, value can be achieved in conjunction with a certain corresponding discharge advantageously a temperature compensation of Einspritz attachenschaften the fuel injection valve 10 and thus the injected fuel quantity. Changes in the temperature of the actuator 12, such as a change in its electrical capacity, also affect the recharging time At 35S0N . Again, the inventive control of the recharge time At 35S0N for realizing a temperature compensation, ie, for example, to keep constant a predetermined recharge time At 35S0N .
• the use according to the invention of the voltage swing and the recharging time as a control variable also advantageously avoids the need for direct regulation of the corresponding currents I E , I L , which is disadvantageous due to a usually relatively low accuracy in the metrological detection of the currents.
• the quantities required for the control according to the invention actuator voltage U and time t can be detected very precisely contrast and allow a correspondingly precise control.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Fuel-Injection Apparatus (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

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• 2006
  • 2006-12-12 DE DE102006058744A patent/DE102006058744A1/de not_active Withdrawn
• 2007
  • 2007-11-12 US US12/304,589 patent/US8082903B2/en not_active Expired - Fee Related
  • 2007-11-12 JP JP2009540685A patent/JP4868554B2/ja not_active Expired - Fee Related
  • 2007-11-12 CN CN2007800459203A patent/CN101558228B/zh not_active Expired - Fee Related
  • 2007-11-12 EP EP07822494.6A patent/EP2100020B1/de not_active Not-in-force
  • 2007-11-12 WO PCT/EP2007/062208 patent/WO2008071507A1/de active Application Filing

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